The 2nd US Cavalry Regiment was authorized by an Act of Congress on March 2, 1855. Often referred to as "Jeff Davis's Own," the unit was an elite organization. The officers assigned to the 2nd Cavalry were handpicked by Secretary of War Jefferson Davis; the majority of them, like Davis, were Southerners by birth and West Point Graduates by education. The noncommissioned officers were specially selected from the other mounted regiments, and the privates were recruited mainly from Midwestern and Southern states. Horses for the regiment were purchased by a special team of 2nd Cavalry officers who were authorized to buy the best-blooded stock available in Kentucky, Indiana and Ohio. For purposes of appearance and to engender esprit de corps each company was assigned horses of one color. In concert with the high standards set in selecting the men and mounts the regiment was furnished with the newest and best arms, accouterments and equipment.

After the end of the Civil War the regimental headquarters of the 2nd Cavalry was established in Omaha, Nebraska, and following Custer's Battle at the Little Big Horn the headquarters were moved to Fort Custer, Montana.

In June of 1876 one battalion of the 2nd Regiment nearly joined Custer before the Battle of the Little Big Horn. Lieutenant Colonel George A. Custer of the 7th Cavalry was offered the use of the "Montana Battalion" of the 2nd Regiment, but he declined the offer. On June 25 Custer stumbled into a force of Sioux warriors that killed every officer, soldier, and civilian in Custer's wing of the 7th Cavalry. Two days later, the Montana Battalion discovered the evidence of Custer's fate.

Thanks largely to the work of the 2nd Cavalry, the Indian battles drew to a close soon after the Battle of the Little Big Horn. On October 4, 1877 Chief Joseph of the Nez Perce tribe surrendered to General OO Howard. The Cheyenne surrendered in December of 1877 and Crazy Horse surrendered in April of 1878. The Cheyenne Chief, Little Wolf, was encamped at Box Elder Creek, Montana when Lieutenant William P. Clark, who had developed a special rapport with the Indians, was able to negotiate with the chief and his band and persuade them to return under escort to Fort McKeogh. The Army enlisted several of the men as scouts, allowing them to stay in the north.

The 2nd US Cavalry is the longest consecutive active unit in US Army history and has produced more generals than any other unit, as well as 13 Medal of Honor winners.

The 2nd US Cavalry Association, founded in July of 2003, is a living history organization dedicated to the preservation of the customs, living conditions, lifestyle and manner of military dress of the Montana Cavalry trooper from 1865 to 1901. The association encourages the study, research and instruction of Cavalry life in a living history format to assure the continued remembrance of Montana’s proud military heritage.